The invention relates to a nozzle assembly for gas-dynamic high efficiency lasers with a cooling system. Such lasers may be of the so-called continuous pulse or of the continuous wave type.
Nozzle assemblies which comprise a plurality of individual nozzle members or lamellae are already known as such. Thus, U.S. Pat. No. 3,602,432 discloses a multiple nozzle arrangement for gas-dynamic lasers, wherein the individual nozzle members are arranged one upon the other in the flow canal. The nozzle members are held and fixed by means of setting pins. A cooling system for each individual nozzle member is not provided in U.S. Pat. No. 3,602,432. The disclosed support or holding means and the lack of sufficient cooling in said U.S. Patent do not permit, however, the maintaining of predetermined or optium nozzle contours, especially of the nozzle throat during continuous operation. However, maintaining the nozzle contours is important for assuring a satisfactory inversion in the laser gas and a prerequisite for an optimal parallel flow for producing an optimal laser beam.
A cooling system for a rod-shaped stimulatable solid state laser has been disclosed in German Patent Publication (DAS) No. 2,263,084. The excitation light source of this solid state laser is located in good thermal conducting contact with a cylindrical housing of a concave mirror reflector, which is itself located in a cooling circuit, and wherein the thermal conducting contact comprises a bank of leaf springs. This type of heat dissipation is, however, not usable for gas-dynamic lasers, not to mention the quite considerable weight increase.
A gas dynamic CO.sub.2 laser has been disclosed in German Patent Publication (DOS) No. 2,241,428, the expansion device of which comprises a plurality of lamella-like, small Laval nozzles arranged in parallel to each other at a combustion chamber, and the support means of which have cooling canals which are in contact with the cooling canals of the individual lamellae. It has since been found that such a cooling system is not sufficient for a continuous operation of a high efficiency laser, because even a slight temperature rise of the lamellae causes a strong cross sectional change of the nozzle throat. This leads to the formation of varying nozzle canals or channels and hence to a non-parallel gas flow.